Gang Leader Tied to Tupac Murder Case Gets 10 Years in Prison in Drug Case

The reputed gang leader connected to Tupac's murder case is finally gonna do hard time -- but for a completely separate case ... TMZ has learned.

Darnell Brim is getting 10 years in federal prison after ATF agents caught him trying to sell crack cocaine. Brim is believed to be one of 4 men who were riding in the white Cadillac that pulled up to Suge Knight's car in 1996 in Las Vegas. Someone in that car opened fire, killing Tupac.

Brim was busted during a 2013 sting operation. He pled guilty to 2 felonies -- conspiracy to distribute crack and distribution of crack.

As you well know by now, Tupac's murder has never been solved, but according to 1996 LAPD records, investigators believed Brim -- a notorious South Side Compton Crips leader -- was in the white Caddy that was "used by the suspect(s) who shot Tupac Shakur."

Although he was never charged in the case, Brim was hit in a Compton drive-by shooting just 2 days after Tupac's murder -- and cops believe it was retaliation for Pac.